Method Signature Test

//
//  main.m
//  MethodSignatureTest
//
//  Created by Jayson Rhynas on 2017-04-03.
//  Copyright © 2017 Jayson Rhynas. All rights reserved.
//

#import <Foundation/Foundation.h>

typedef struct Struct1 {
    int *member;
} Struct1;

typedef struct Struct2 {
    Struct1 member;
} Struct2;

// This struct cannot be encoded
typedef struct Struct3 {
    Struct1 *member;
} Struct3;

@interface MethodSignatureTest : NSObject
@end

@implementation MethodSignatureTest

- (instancetype)init
{
    if (!(self = [super init])) return nil;
    
    NSLog(@"%@", [self methodSignatureForSelector:@selector(testMethod1:)]); // Works
    NSLog(@"%@", [self methodSignatureForSelector:@selector(testMethod2:)]); // Works
    NSLog(@"%@", [self methodSignatureForSelector:@selector(testMethod3:)]); // Crashes here
    
    return self;
}

- (void)testMethod1:(Struct1)strct {}
- (void)testMethod2:(Struct2)strct {}
- (void)testMethod3:(Struct3)strct {}

@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        [[MethodSignatureTest alloc] init];
    }
    return 0;
}

Crashes at line 34 with

NSInvalidArgumentException: NSGetSizeAndAlignment(): unsupported type encoding spec 'u' at 'ruct1}}16' in '{Struct1}}16'

Full output of @encode(Struct3) is {Struct3=^{Struct1}}

I can work around it by making the pointer to Struct1 a void * and casting where appropriate, but that's a pain and more error prone.